This research aims to investigate the effects of age and sex on some acoustic features of speech sounds including fundamental frequency (F0), formants (F1 and F2), intensity and duration. To do this, twenty four Persian-speaking participants (12 male and 12 female) were asked to utter 36 CVC isolated words. Syllables consisted of six Persian plosives /p/, /t/, /k/, /b/, /d/ and /g/ and six vowels /æ/, /e/, /!/,/"/, /u/ and /#/; thus, every syllable had two similar plosives plus a vowel in between. Syllables were recorded in a sound-proof room using Praat Software. All acoustic properties were measured using spectrogram and oscillogram. Results showed that duration of vowels in teenagers was longer than that in adults; moreover, females had longer duration than males. Concerning formants, F1 of all vowels was more in children than in adults except for /o/. Intensity of men was more than that of women and F0 was less in middle-aged people than in young people and it was more in women than in men.